Method and apparatus for position determination in a cellular communications system

ABSTRACT

A scaling apparatus and method scales uncertainty criteria (horizontal and vertical accuracy requirements) originally received from an end user before the uncertainty criteria is sent on to a wireless terminal ( 30 ) as requirements on the accuracy of location positioning performed by/for the wireless terminal. In an example embodiment the amount/degree of scaling is selected according to a configured best estimate of the confidence and uncertainty relation, and such best estimate can be based on the majority of the terminals of the network. For a WCDMA radio access network (RAN) case the scaling can be performed in a radio network controller (RNC). For a Long Term Evolution (LTE) radio access network (RAN) case the scaling can be performed in the evolved Serving Mobile Location Center (eSMLC) node. In another case the scaling can alternatively be performed in the wireless terminal itself.

This application claims the priority and benefit of U.S. ProvisionalPatent Application 61/291,101, filed Dec. 30, 2009, entitled “METHOD ANDAPPARATUS FOR POSITION DETERMINATION IN A CELLULAR COMMUNICATIONSSYSTEM”, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

This invention pertains to telecommunications, and in particular tomethods and apparatus for determining and/or reporting a position of aterminal such as a wireless terminal.

BACKGROUND

Determination of position location can be important for many differenttypes of equipment, particularly for mobile units or vehicles. Forexample, determination of position location can allow the user of themobile unit or vehicle to ascertain the user's whereabouts, enabling theuser to make appropriate navigation or other decisions. In addition,when provided to a third party, information regarding position locationof a mobile unit or vehicle can enable the third party to locate andprovide assistance or render service to the user.

1.0 Radio Access Networks

One example of a mobile unit for which position location can beimportant is a wireless terminal of a telecommunications system. Infact, governmental agencies of some countries mandate that communicationcarriers provide emergency service providers with highly accurateinformation of mobile units in a timely manner. An example of suchrequirement is the United States Federal Communications Commission E-911mandate.

In a typical cellular radio system, such wireless terminals (also knownas mobile stations and/or user equipment units (UEs)) communicate via aradio access network (RAN) to one or more core networks. The radioaccess network (RAN) covers a geographical area which is divided intocell areas, with each cell area being served by a base station, e.g., aradio base station (RBS). In some networks a base station may also becalled a “NodeB” (UMTS) or “eNodeB” (LTE). A cell is a geographical areawhere radio coverage is provided by the radio base station equipment ata base station site. Each cell is identified by an identity within thelocal radio area, which is broadcast in the cell. The base stationscommunicate over the air interface operating on radio frequencies withthe user equipment units (UE) within range of the base stations.

In some versions of the radio access network, several base stations aretypically connected (e.g., by landlines or microwave) to a controllernode (such as a radio network controller (RNC) or a base stationcontroller (BSC)) which supervises and coordinates various activities ofthe plural base stations connected thereto. The radio networkcontrollers are typically connected to one or more core networks.

The Universal Mobile Telecommunications System (UMTS) is a thirdgeneration mobile communication system, which evolved from the secondgeneration (2G) Global System for Mobile Communications (GSM). UTRAN isessentially a radio access network using wideband code division multipleaccess for user equipment units (UEs).

In a forum known as the Third Generation Partnership Project (3GPP),telecommunications suppliers propose and agree upon standards for thirdgeneration networks and UTRAN specifically, and investigate enhanceddata rate and radio capacity. Specifications for the Evolved UniversalTerrestrial Radio Access Network (E-UTRAN) are ongoing within the 3^(rd)Generation Partnership Project (3GPP). The Evolved Universal TerrestrialRadio Access Network (E-UTRAN) comprises the Long Term Evolution (LTE)and System Architecture Evolution (SAE). Long Term Evolution (LTE) is avariant of a 3GPP radio access technology wherein the radio base stationnodes are connected to a core network (via Serving Gateways, or SGWs)rather than to radio network controller (RNC) nodes. In general, in LTEthe functions of a radio network controller (RNC) node are distributedbetween the radio base stations nodes (eNodeB's in LTE) and SGWs. Assuch, the radio access network (RAN) of an LTE system has an essentially“flat” architecture comprising radio base station nodes withoutreporting to radio network controller (RNC) nodes.

2.0 Positioning Methods

There are several positioning methods which can be used to determine theposition of a wireless terminal. Among such positioning methods areAssisted GPS (A-GPS), Observed Time Difference of Arrival (OTDOA), andAdaptive Enhanced Cell ID (AECID). Each of these positioning methods isdescribed briefly below.

2.1 A-GPS

Assisted GPS (A-GPS) positioning is an enhancement of the globalpositioning system (GPS). A-GPS allows much faster location by usingmore precise positioning information obtained from stations (e.g., basestations) that monitor GPS satellites essentially constantly. Thisinformation is called “assistance data” or “acquisition assistance data”and allows the wireless terminal to determine and report back to thenetwork its location within seconds. GPS reference receivers attached toa cellular communication system collect assistance data that, whentransmitted to GPS receivers in terminals connected to the cellularcommunication system, enhance the performance of the GPS terminalreceivers.

There are two basic types of A-GPS. One type, denoted “UE-based A-GPS”,relies on the user equipment unit (UE) for calculation of the position.The position is reported back to the eNodeB and a node known as theevolved Serving Mobile Location Center (eSMLC) using one of severalpossible 3GPP reporting formats (some 3GPP reporting formats arediscussed below). Another type, denoted “UE-assisted A-GPS”, relies onthe wireless terminal (UE) to perform measurements of so calledpseudo-ranges. The wireless terminal then reports said pseudo-rangemeasurements back to the evolved Serving Mobile Location Center (eSMLC)where the position calculation is being performed. For UE-based A-GPSthe point with uncertainty circle format is affected by a lack ofconfidence information.

2.2 OTDOA

The OTDOA positioning method that is currently being standardized in3GPP for the LTE cellular system operates according to similarprinciples as A-GPS. The wireless terminal (UE) performs time of arrivalmeasurements on signals from several neighbor eNodeBs, the signals beingdesigned for positioning purposes. Since it is generally not assumedthat the system is synchronized, the eNodeBs also perform measurementsof the time of transmission of said signals. The distance from theeNodeB to the UE can be related to the time of arrival, the time oftransmission and the unknown clock bias of the UE with respect to thecellular time base. Since the 2-dimensional (2D) coordinates of the UEare the sought unknowns, at least three such relations need to beestablished in order to be able to solve for said coordinates and theunknown clock bias. It is common practice to form pair-wise differencesbetween such relations, thereby eliminating the clock bias which is thesame in all equations. This generates time difference of arrivalmeasurements.

There are two basic types of OTDOA methods. One type (denoted “UE-basedOTDOA”) relies on the user equipment unit (UE) or wireless terminal forcalculation of the position. The position is reported back to the eNodeBand the eSMLC using one of the 3GPP reporting formats. Another type(denoted “UE-assisted OTDOA”) relies on the user equipment unit (UE) orwireless terminal to perform time of arrival measurements. The wirelessterminal then reports said difference time of arrival measurements backto the evolved Serving Mobile Location Center (eSMLC) where the positioncalculation is being performed. For UE-based OTDOA the point withuncertainty circle format is affected by a lack of confidenceinformation. For the LTE cellular system the standard is yet limited toUE-assisted OTDOA.

2.3 AECID

Adaptive Enhanced Cell ID (AECID) is a fingerprinting positioningmethod. In the radio fingerprint mapping mode high precision referencepositions of opportunity are generated either by A-GPS or OTDOApositioning It can be noted that OTDOA provides high precisionmeasurements also indoors. At the same time as the reference positionsare obtained the AECID positioning method performs measurements of theradio conditions experienced by the wireless terminal, the measurementsbeing denoted radio fingerprints. For Long Term Evolution (LTE), theradio fingerprinting measurements may consist of a subset of the servingcell ID, the timing advance value (TA), detected neighbor cell IDs,signal strengths/pathloss with respect to neighbor eNodeBs, as well asangle of arrival measurements. The radio fingerprint measurements arethen processed further and combined in order to produce a radiofingerprint tag, associated with said high precision reference position.All tagged reference positions with the same tag are then collected intagged clusters and stored, preferably in a hierarchical database. In afinal step a 3GPP polygon is computed according to a certain algorithmthat describes the boundary of said tagged cluster. The algorithm isdescribed in T. Wigren, “Adaptive enhanced cell-ID fingerprintinglocalization by clustering of precise position measurements”, IEEETrans. Veh. Tech., vol 56, No. 5, pp. 3199-3209, 2007, which isincorporated by reference herein in its entirety. This tagged polygon ispreferably stored in a hierarchical database. It is a special propertyof the algorithm that the polygons are computed to have a specificconfidence, the confidence being determined from the live measured highprecision measurements of said tagged cluster. When a positioningrequest is received in the positioning node, the list of own andneighbor cell IDs and the timing advance value are retrieved, and signalstrength and angle of arrival measurements are performed and quantized.This information creates the tag of the terminal. The polygon thatcorresponds to the tag is collected from the database and reported. Thisis denoted the positioning mode.

3.0 Position Parameter Reporting

One or more of the aforementioned positioning methods require thatcertain general parameters be reported to a node or system which assistsin or makes the determination of the wireless terminal location. Formost positioning methods and situations the general parameters include areported position parameter and a reported uncertainty parameter. Forsimplicity these two general parameters are also referenced herein asthe “position” and “uncertainty”.

3.1 Position

The “position” is generally considered to be a “point” at which thewireless terminal or UE is thought to be located. As explainedhereinafter, position can be reported in one of several formats.

3.2 Uncertainty

Uncertainty can be reported in various ways, some of which are describedbelow. In the 3GPP LTE specification, uncertainty can be reported interms of an uncertainty circle, an uncertainty ellipse, an uncertaintyellipsoid, as well as by the reported regions themselves when thereported regions are given by the ellipsoid arc and polygon formats.See, e.g., 3GPP, TS 23.032, “Universal Geographical Area Description(GAD)”, available at http://www.3gpp.org, incorporated herein byreference. Often uncertainty is expressed in terms of horizontal (horz)and vertical (vert) inaccuracies, the horizontal inaccuracy being usedin a two dimensional (2D) case and both the horizontal inaccuracy andthe vertical inaccuracy being used in a three dimensional (3D) case.

3.3 Confidence/Probability

Accuracy in the radio navigation field, particularly for A-GPS and OTDOApositioning in LTE, is a random quantity. In view of the randomness ofaccuracy, the uncertainty is sometimes accompanied with a correspondingprobability or “confidence” that the terminal is actually in the regiondefined by the reported position and the reported uncertainty. Thus, forsome positioning methods and situations a third parameter (known as the“probability” or “confidence” parameter) is also reported. Theconfidence parameter indicates the probability that the terminal islocated in the interior of the reported region.

The ways the confidence parameter is obtained can differ for differingpositioning methods. A reason that confidence parameters are obtaineddifferently is due to use of different statistical models employed forthe respective positioning methods. In A-GPS, inaccuracy is caused by acombination of pseudo-range measurement errors and geometrical effects.Due to the excess measurements employed with A-GPS, the law of largenumbers together with a linearization provides a motivation for thestandard Gaussian position error model. Also OTDOA preferably exploitsthe Gaussian uncertainty model. For AECID positioning the error isinstead caused by radio coverage effects, so that a uniform statisticalmodel for the terminal location is used for the AECID cases.

4.0 Location Reporting

Various messages involved with the determination of position locationand reporting formats are now described. The following descriptionassumes that UE-based versions of A-GPS or OTDOA are used for Long TermEvolution (LTE).

4.1 Downlink Messages 4.1.1 UMTS Downlink Messages

In the downlink the LOCATION REPORTING CONTROL message is obtained inthe RNC over the RANAP interface. See, e.g., 3GPP, TS25.413, “UTRAN Iuinterface RANAP signaling”, available at http://www.3gpp.org,incorporated herein by reference. Also in the downlink, the MEASUREMENTCONTROL message is sent from the radio network controller (RNC) to theuser equipment unit (UE). See, e.g., 3GPP, TS 25.331, “Radio ResourceControl (RRC)”, available at http://www.3gpp.org, incorporated herein byreference.

The LOCATION REPORTING CONTROL message and the MEASUREMENT CONTROLmessage each include an accuracy code and a vertical accuracy code. Theaccuracy code, representing horizontal accuracy, is expressed as a codevalue (0-127) that represents the radius of an uncertainty circle. Thevertical accuracy code is expressed as a code value (0-127) thatrepresents an altitude uncertainty in meters, encoded differently thanthe horizontal accuracy.

4.1.2 LTE Downlink Messages

In the downlink the GMLC sends a PROVIDE SUBSCRIBER LOCATION REQUESTmessage to the MME, see 3GPP TS 25.172 “Evolved Packet Core (EPC) LCSProtocol (ELP) between the Gateway Mobile Location Centre (GMLC) and theMobile Management Entity (MME); SLg interface”, available athttp://www.3gpp.org, incorporated herein by reference. The MME sends theLOCATION REQUEST message to the E-SMLC, see 3GPP TS 25.171 “LCSApplication Protocol (LCS-AP) between the Mobile Management Entity (MME)and Evolved Serving Mobile Location Centre (E-SMLC); SLs interface”,available at http://www.3gpp.org, incorporated herein by reference. TheE-SMLC sends the REQUEST LOCATION INFORMATION message to the UE, see3GPP TS 36.355, “LTE Positioning Protocol (LPP)”, available athttp://www.3gpp.org, incorporated herein by reference.

The PROVIDE SUBSCRIBER LOCATION message, the LOCATION REQUEST messageand the REQUEST LOCATION INFORMATION message each include an accuracycode and a vertical accuracy code. The accuracy code, representinghorizontal accuracy, is expressed as a code value (0-127) thatrepresents the radius of an uncertainty circle. The vertical accuracycode is expressed as a code value (0-127) that represents an altitudeuncertainty in meters, encoded differently than the horizontal accuracy.

4.2 Uplink Messages 4.2.1 UMTS Uplink Messages

In the uplink the MEASUREMENT REPORT message is sent to the radionetwork controller (RNC) over the RRC interface. See, e.g., 3GPP, TS25.331, “Radio Resource Control (RRC)”, available athttp://www.3gpp.org. Also in the uplink a LOCATION REPORT message issent from the radio network controller (RNC) to the core network. See,e.g., 3GPP, TS25.413, “UTRAN Iu interface RANAP signaling”, available athttp://www.3gpp.org.

4.2.2 LTE Uplink Messages

In the uplink the user equipment unit (UE) sends the PROVIDE LOCATIONINFORMATION message to the E-SMLC, see 3GPP TS 36.355, “LTE PositioningProtocol (LPP)”, available at http://www.3gpp.org, incorporated hereinby reference. The E-SMLC sends the LOCATION RESPONSE message to the MME,see 3GPP TS 25.171 “LCS Application Protocol (LCS-AP) between the MobileManagement Entity (MME) and Evolved Serving Mobile Location Centre(E-SMLC); SLs interface”, available at http://www.3gpp.org, incorporatedherein by reference. The MME sends a PROVIDE SUBSCRIBER LOCATIONRESPONSE message to the GMLC, see 3GPP TS 25.172 “Evolved Packet Core(EPC) LCS Protocol (ELP) between the Gateway Mobile Location Centre(GMLC) and the Mobile Management Entity (MME); SLg interface”, availableat http://www.3gpp.org, incorporated herein by reference.

5.0 Reporting Formats

Position information in any of several reporting formats can be includedin an information element in an appropriate message. Example,non-exhaustive reporting formats are listed below. For UMTS the lastfive of the following reporting formats can be included in theMEASUREMENT REPORT message and the LOCATION REPORT message. For UMTS thefifth and seventh reporting formats can be included in the MEASUREMENTREPORT message and the LOCATION REPORT message for the A-GPS method, andare respectively associated with two dimensional and three dimensionalreporting. For LTE the last five of the following reporting formats canbe included in the PROVIDE LOCATION INFORMATION message, the LOCATIONRESPONSE and the PROVIDE LOCATION INFORMATION message. The fifth andseventh reporting formats can be included in the PROVIDE LOCATIONINFORMATION message, the LOCATION RESPONSE and the PROVIDE LOCATIONINFORMATION message for the A-GPS method, and are respectivelyassociated with two dimensional and three dimensional reporting.

5.1 Polygon

The polygon format is described by a list of 3-15 latitude, longitudecorners, encoded in WGS 84 co-ordinates. See, e.g., 3GPP, TS 23.032,“Universal Geographical Area Description (GAD),” available athttp://www.3gpp.org. The polygon format does not carry confidenceinformation. This format may be obtained by application of cell IDpositioning and AECID positioning in LTE.

5.2 Ellipsoid Arc

The ellipsoid arc is described by a center point (eNodeB antennaposition), encoded as latitude, longitude in WGS 84 co-ordinates.Furthermore, the format contains an inner radius of the arc, a thicknessof the arc as well as the offset angle (clockwise from north) and theincluded angle (opening angle). Together, these parameters define acircular sector, with a thickness and with left and right angles. See,e.g., 3GPP, TS 23.032, “Universal Geographical Area Description (GAD),”available at http://www.3gpp.org, incorporated herein by reference. Theellipsoid arc does carry confidence information. This format isproduced, e.g., by cell ID+TA positioning in LTE.

5.3 Ellipsoid Point

The ellipsoid point format is described by a center point, encoded aslatitude, longitude in WGS 84 co-ordinates. The format neither carriesuncertainty, nor confidence information.

5.4 Ellipsoid Point with Uncertainty Circle

The ellipsoid point with uncertainty circle format consists of a centerpoint, encoded as latitude, longitude in WGS 84 co-ordinates, incombination with a radial uncertainty radius, encoded as in 3GPP, TS23.032, “Universal Geographical Area Description (GAD),” available athttp://www.3gpp.org. The format does not carry confidence information.This is addressed by particular embodiments of the present invention.

5.5 Ellipsoid Point with Uncertainty Ellipse (Confidence Included)

The ellipsoid point with uncertainty ellipse format consists of a centerpoint, encoded as latitude, longitude in WGS 84 co-ordinates. Theuncertainty ellipse is encoded as a semi-major axis, a semi-minor axisand an angle relative to north, counted clockwise from the semi-majoraxis, see 3GPP, TS 23.032, “Universal Geographical Area Description(GAD),” available at http://www.3gpp.org, incorporated herein byreference. The format carries confidence information. This format istypically produced by OTDOA and A-GPS positioning in LTE.

5.6 Ellipsoid Point with Altitude

The ellipsoid point with altitude format is encoded as an ellipsoidpoint, together with an encoded altitude, see 3GPP, TS 23.032,“Universal Geographical Area Description (GAD),” available athttp://www.3gpp.org, incorporated herein by reference. The formatneither carries uncertainty, nor confidence information.

5.7 Ellipsoid Point with Altitude and Uncertainty Ellipsoid (ConfidenceIncluded)

The ellipsoid point with altitude and uncertainty ellipsoid (confidenceincluded) format is the format commonly received from A-GPS capableterminals. It consists of an ellipsoid point with altitude and anuncertainty ellipsoid, the latter encoded with a semi-major axis, asemi-minor axis, an angle relative to north, counted clockwise from thesemi-major axis, together with an uncertainty altitude, see 3GPP, TS23.032, “Universal Geographical Area Description (GAD),” available athttp://www.3gpp.org, incorporated herein by reference. The formatcarries confidence information. This format is typically produced byA-GPS positioning in LTE.

6.0 Rescaling

Examples of the calculations in the user equipment unit (UE) that may beused to determine the position and the corresponding inaccuracy for theUE-based A-GPS and the UE-based OTDOA methods can be found in, e.g., E.D. Kaplan, Understanding GPS-Principles and Applications, Norwood,Mass.: Artech House, 1996, incorporated herein by reference. For presentpurposes it is sufficient to note that the user equipment unit (UE)measures the time of arrival of signals transmitted from multiple GPSsatellites, or eNodeBs. The orbits and positions of these satellites areavailable with very high precision since this information is transmittedto the terminal as assistance data in A-GPS positioning Such assistancedata can comprise, e.g., trajectory models that describe the orbits ofthe satellites.

The pseudoranges measured with respect to the satellites can then becombined to compute the position of the terminal By doing alinearization of the nonlinear measurement geometry and treating thetime measurement errors as randomly identically distributed, acovariance matrix describing the uncertainty can be calculated. Thecovariance matrix is the second moment of the almost Gaussianuncertainty (follows by the strong law of large numbers). Thiscovariance matrix represents an ellipse in the two dimensional (2D)horizontal case and an ellipsoid in the three dimensional (3D) case.

In particular embodiments, the aforementioned covariance matrices areassociated with confidence values of 39% (2-dimensional case) and 20%(3-dimensional case), respectively. However, the report from the userequipment unit (UE) to network node (either the evolved Serving MobileLocation Center (eSMLC) for the LTE radio access network (RAN) or to theradio network controller (RNC) for the WCDMA radio access network (RAN))may use any of the last five formats listed in section 5.0 above. Ofthose reporting formats, neither the ellipsoid point, the ellipsoidpoint with uncertainty circle, nor the ellipsoid point with altitudecarry confidence information. Hence, it cannot be guaranteed that aconfidence value is available in the network node (e.g., eSMLC or RNC)for re-scaling or shape conversion of the obtained result.

When the measured position and uncertainty are received in a networknode (such as the RNC in a WCDMA network and the evolved Serving MobileLocation Center (eSMLC) node in a LTE network) the network node mayattempt to perform a shape conversion. In particular, the network nodemay attempt to scale the received uncertainty so that the confidencevalue of the scaled uncertainty becomes equal to the confidence valuethat is configured for reporting to the core network for the specificservice valid for the ongoing positioning. See, e.g., A. Kangas and T.Wigren, “Transformation of Positioning reporting formats”, InternationalPatent Application, PCT/SE2007/050237/Apr. 11, 2007, which isincorporated herein by reference. This scaling attempt thus requiresknowledge of the confidence of the transformed reporting format. Butsignificantly, as indicated above, for some reporting formats theconfidence parameter is not reported/provided.

Thus, with the existing state of technology various reporting formats(particularly including the polygon reporting format and the ellipsoidpoint with uncertainty circle reporting format) lack informationelements that carry confidence information. The polygon reporting formatis pertinent to the AECID positioning method. Unfortunately the polygonformat presently specified by 3GPP does not carry confidenceinformation, this reducing the flexibility of the reporting to the enduser (polygon computation is normally performed in the AECID positioningnode).

A reporting format that does not include confidence information does notcarry enough information to allow a correct scaling of the uncertaintyof the reported result. The scaling is performed in a node such as theradio network controller (RNC) in WCDMA and the evolved Serving MobileLocation Center (eSMLC) node in Long Term Evolution (LTE). Withoutconfidence information to allow correct scaling there is a significantdanger that the quality of service (QoS) of the requested position iserroneously classified as not being satisfied. This may then affectreported results from the node (e.g., RNC or eSMLC) as well as thestepping of internal counters. These counters, whose values may beadversely affected by the lack of confidence information and incorrectscaling, are important since the counters provide statistics onregulatory E-911 positioning performance to regulatory agencies such asthe United States Federal Communications Commission.

The consequence of not having confidence information is that positioningresults for the A-GPS, OTDOA, cell ID and AECID positioning methods maynot be properly reported. More precisely the reported accuracy may notbe scaled according to the measured and requested confidence values.Furthermore, the confidence of the reported positioning result cannot bereported to the end user for the AECID method, and may not be reportedto the end user for the A-GPS and OTDOA positioning methods.

Another problem with prior art technology is that sometimes the terminal(e.g., user equipment unit (UE)) may determine an A-GPS position anduncertainty that exactly matches the requested horizontal and verticalaccuracy that is received from the RNC. Normally the user equipment unit(UE) then responds with a confidence value of 39% or 20% in the 2D and3D cases, respectively. Most often the configured confidence to bereported to the end user from the RNC or eSMLC is significantly higher,in emergency positioning typically 95%. In such case the RNC or eSMLCtypically scales up the uncertainty region obtained from the wirelessterminal to comply with the higher confidence value. The result is thenan uncertainty region that is higher than what was originally requestedby the end user, this resulting in a failure to meet the requestedquality of service (QoS). This is then recorded in statistics, and alsosignaled to the end user, resulting in increased customer complaints.

SUMMARY

In one of its aspects the technology disclosed herein concerns methodand apparatus for generating/transmitting/processing a positionreporting message of a type which expresses position of a wirelessterminal in either (1) a polygon report format, or (2) an ellipsoidpoint with uncertainty circle format. In such aspect the technologydisclosed herein particularly concerns, e.g., inclusion of a confidenceparameter (e.g., as an information element of the position reportingmessage) in addition to a reported position parameter and reporteduncertainty parameter.

In another of its aspects the technology disclosed herein concerns acommunications device which receives a position request messageconfigured to request determination of a position of a wireless terminalThe position request message includes a position uncertainty criteria.The device is configured to know that a confidence differential existsbetween a confidence reporting characteristic of the wireless terminaland confidence criteria known to the communications device. As a resultof the confidence differential, the device is configured to scale theposition uncertainty criteria to obtain a scaled position uncertaintycriteria for use by the wireless terminal.

In differing embodiments, the confidence criteria is known to thecommunications device either by being included in the position requestmessage or (as in the case of WCDMA) by being configured in thecommunications device.

In an example embodiment and implementation, the communications deviceis configured to scale the position uncertainty criteria in accordancewith the confidence differential to obtain the scaled positionuncertainty criteria.

In an example embodiment, the device is configured to transmit thescaled position uncertainty criteria to the wireless terminal, and isfurther configured to receive back from the wireless terminalinformation comprising a reported position uncertainty parameter and areported confidence parameter. The device is further configured tore-scale the reported position uncertainty parameter in a manner so thatthe position uncertainty criteria is satisfied. The reported positionuncertainty parameter is based on the scaled position uncertaintycriteria and the reported confidence parameter is based on theconfidence reporting characteristic of the wireless terminal As anexample, the device can be configured to re-scale the reported positionuncertainty parameter in accordance with the confidence differential. Inan example implementation suitable for a WCDMA radio access network(RAN), the device comprises a radio network controller (RNC) node. Inanother example implementation suitable for use with a Long TermEvolution (LTE) radio access network (RAN), the device comprises anevolved Serving Mobile Location Center (eSMLC) node.

In another example embodiment the communications device is the wirelessterminal itself. The wireless terminal is configured to use the scaledposition uncertainty criteria to determine a position parameter, aposition uncertainty parameter, and a confidence parameter. The scaledposition uncertainty criteria is used as an input for the A-GPS positiondetermination since, e.g., the terminal will try and meet the scaledposition uncertainty criteria (it may, e.g., continue longer if thiscriterion is more difficult to meet). The position uncertainty parameterwhich is output from the A-GPS determination can be but need notnecessarily be the same as the scaled position uncertainty criteria(e.g., it may be less than or equal or larger.) The wireless terminal isfurther configured to re-scale the reported position uncertaintyparameter to form a re-scaled uncertainty parameter that satisfies theposition uncertainty criteria, and to generate a position reportcomprising the position parameter, the re-scaled uncertainty parameter,and the confidence parameter.

In an example implementation, the wireless terminal is configured togenerate the position report wherein the position parameter is expressedin a polygon report format, and wherein the polygon report formatincludes an information element comprising the reported confidenceparameter. In another example implementation, the wireless terminal isconfigured to generate the position report wherein the positionparameter is expressed in an ellipsoid point with uncertainty circlereport format, and wherein the ellipsoid point with uncertainty circlereport format includes an information element comprising the reportedconfidence parameter.

In an example embodiment the device comprises a computer-implementedscaler configured to scale the position uncertainty criteria to obtainthe scaled position uncertainty criteria for use by the wirelessterminal.

In yet another of its aspects the technology disclosed herein comprisesa method of operating a communications device. An act of the generalmethod comprises receiving at a network device a position requestmessage configured to request determination of a position of a wirelessterminal The position request message includes position uncertaintycriteria. Another act of the general method comprises the devicedetermining that a confidence differential exists between a confidencereporting characteristic of the wireless terminal and confidencecriteria known to the communications device. As a result of theconfidence differential, another act of the general method comprises thedevice scaling the position uncertainty criteria to obtain scaledposition uncertainty criteria for use by the wireless terminal.

In differing embodiments, the confidence criteria is known to thecommunications device either by being included in the position requestmessage or (as in the case of WCDMA) by being configured in thecommunications device.

In an example embodiment and mode the method further comprises scalingthe position uncertainty criteria in accordance with the confidencedifferential to obtain the scaled position uncertainty criteria.

In an example embodiment and mode the method of further comprises:transmitting the scaled position uncertainty criteria to the wirelessterminal; receiving from the wireless terminal information comprising areported position uncertainty parameter and a reported confidenceparameter, the reported position uncertainty parameter being based onthe scaled position uncertainty criteria and the reported confidenceparameter being based on the confidence reporting characteristic of thewireless terminal; and re-scaling the reported position uncertaintyparameter in a manner so that the position uncertainty criteria issatisfied. The reported position uncertainty parameter is based on thescaled position uncertainty criteria and the reported confidenceparameter is based on the confidence reporting characteristic of thewireless terminal. For example, in an example implementation the methodfurther comprises re-scaling the reported position uncertainty parameterin accordance with the confidence differential. In one exampleimplementation the method further comprises performing the scaling at aradio network controller (RNC) node. In another example implementationthe method further comprises performing the scaling at an evolvedServing Mobile Location Center (eSMLC) node.

Another example embodiment and mode comprises performing the scaling ata wireless terminal and using the scaled position uncertainty criteriato determine a position parameter, position uncertainty parameter, and aconfidence parameter. The wireless terminal is configured to use thescaled position uncertainty criteria to determine a position parameter,a position uncertainty parameter, and a confidence parameter. The scaledposition uncertainty criteria is used the input for the A-GPS positiondetermination since, e.g., the terminal will try and meet the scaleduncertainty criteria (it may, e.g., continue longer if this criterion ismore difficult to meet). The position uncertainty parameter which isoutput from the A-GPS determination can be but need not necessarily bethe same as the scaled position uncertainty criteria (e.g., it may beless than or equal or larger.) The wireless terminal is furtherconfigured to re-scale the reported position uncertainty parameter toform a re-scaled uncertainty parameter that satisfies the positionuncertainty criteria, and to generate a position report comprising theposition parameter, the re-scaled uncertainty parameter, and theconfidence parameter.

In an example implementation the method further comprises, in theposition report, expressing the position parameter in a polygon reportformat; and, including in the polygon report format an informationelement comprising the reported confidence parameter. In another exampleimplementation the method further comprises, in the position report,expressing the position parameter in an ellipsoid point with uncertaintycircle report format; and, including in the ellipsoid point withuncertainty circle report format an information element comprising thereported confidence parameter. Inclusion of the reported confidenceparameter(s) in the “position report” encompasses and includes inclusionof the confidence parameters in reports that are provided from the eSMLCto the end user.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments as illustrated in the accompanyingdrawings in which reference characters refer to the same partsthroughout the various views. The drawings are not necessarily to scale,emphasis instead being placed upon illustrating the principles of theinvention.

FIG. 1 is a schematic view of portions of a telecommunications systemincluding portions of a Long Term Evolution (LTE) radio access network(RAN) useful for position location determination.

FIG. 2 is a diagrammatic view of message flow in the telecommunicationssystem of FIG. 1 for a mobile terminating location request.

FIG. 3 is a schematic simplified view of a wireless terminal accordingto an example embodiment.

FIG. 4 is a schematic view of a wireless terminal according to amachine-implemented example embodiment.

FIG. 5 is a diagrammatic view of an example SMLC network wherein theSMLC receives a request for assistance data for a particular wirelessterminal and wherein the data includes confidence information.

FIG. 6 is a diagrammatic view of an example A-GPS positioning systemwherein acquisition assistance data includes confidence information.

FIG. 7A is a diagrammatic view of a “polygon” reporting format accordingto an aspect of the technology disclosed herein.

FIG. 7B is a diagrammatic view of an “ellipsoid point with uncertaintycircle” reporting format according to an aspect of the technologydisclosed herein.

FIG. 8 is a diagrammatic view of a representative, generic positiondetermination facilitating device according to an example embodiment.

FIG. 9 is a flowchart illustrating representative, non-limiting acts orsteps involved in a basic position determination facilitation method.

FIG. 10 is a diagrammatic view of a representative example embodiment ofa position determination facilitating device which can take the form ofa node (e.g. network node) such as a radio network controller (RNC) oran evolved Serving Mobile Location Center (eSMLC) node.

FIG. 11 illustrates representative, non-limiting acts or steps involvedin a position determination method involving parameter scaling asperformed by a node such as the node of FIG. 10.

FIG. 12 is a diagrammatic view of a representative example embodiment ofa position determination facilitating device which can take the form ofthe wireless terminal whose position is being sought.

FIG. 13 illustrates representative, non-limiting acts or steps involvedin a position determination method involving parameter scaling asperformed by a wireless terminal such as the wireless terminal of FIG.12.

FIG. 14 is a diagrammatic view of geometry of an uncertainty ellipse.

DETAILED DESCRIPTION

In the following description, for purposes of explanation and notlimitation, specific details are set forth such as particulararchitectures, interfaces, techniques, etc. in order to provide athorough understanding of the present invention. However, it will beapparent to those skilled in the art that the present invention may bepracticed in other embodiments that depart from these specific details.That is, those skilled in the art will be able to devise variousarrangements which, although not explicitly described or shown herein,embody the principles of the invention and are included within itsspirit and scope. In some instances, detailed descriptions of well-knowndevices, circuits, and methods are omitted so as not to obscure thedescription of the present invention with unnecessary detail. Allstatements herein reciting principles, aspects, and embodiments of theinvention, as well as specific examples thereof, are intended toencompass both structural and functional equivalents thereof.Additionally, it is intended that such equivalents include bothcurrently known equivalents as well as equivalents developed in thefuture, i.e., any elements developed that perform the same function,regardless of structure.

Thus, for example, it will be appreciated by those skilled in the artthat block diagrams herein can represent conceptual views ofillustrative circuitry or other functional units embodying theprinciples of the technology. Similarly, it will be appreciated that anyflow charts, state transition diagrams, pseudocode, and the likerepresent various processes which may be substantially represented incomputer readable medium and so executed by a computer or processor,whether or not such computer or processor is explicitly shown.

The functions of the various elements including functional blocks,including but not limited to those labeled or described as “computer”,“processor” or “controller”, may be provided through the use of hardwaresuch as circuit hardware and/or hardware capable of executing softwarein the form of coded instructions stored on computer readable medium.Thus, such functions and illustrated functional blocks are to beunderstood as being either hardware-implemented and/orcomputer-implemented, and thus machine-implemented.

In terms of hardware implementation, the functional blocks may includeor encompass, without limitation, digital signal processor (DSP)hardware, reduced instruction set processor, hardware (e.g., digital oranalog) circuitry including but not limited to application specificintegrated circuit(s) [ASIC], and (where appropriate) state machinescapable of performing such functions.

In terms of computer implementation, a computer is generally understoodto comprise one or more processors or one or more controllers, and theterms computer and processor and controller may be employedinterchangeably herein. When provided by a computer or processor orcontroller, the functions may be provided by a single dedicated computeror processor or controller, by a single shared computer or processor orcontroller, or by a plurality of individual computers or processors orcontrollers, some of which may be shared or distributed. Moreover, useof the term “processor” or “controller” shall also be construed to referto other hardware capable of performing such functions and/or executingsoftware, such as the example hardware recited above.

7.0 Signaling of Confidence Information: Overview

In one of its aspects the technology disclosed herein involves inclusionof confidence information, e.g., probability information, in variousmessages and communications which heretofore omitted the confidenceinformation. For example, this aspect of the technology disclosed hereinencompasses:

-   Addition of a confidence information element to the 3GPP polygon    format: (1) over the relevant interfaces in the Long Term Evolution    (LTE) radio access network (RAN) between the evolved Serving Mobile    Location Center (eSMLC) and the end users; and (2) over the relevant    interfaces in the WCDMA radio access network (RAN) between the radio    network controller (RNC) and the end user.-   Addition of a confidence information element to the 3GPP ellipsoid    point with uncertainty circle format:    -   over the measurement context of the wireless terminal and the        eSMLC;    -   over the position reporting context between the eSMLC and the        end user;    -   over the relevant interfaces in the WCDMA radio access network        (RAN) between the measurement context of the wireless terminal        and the RNC;    -   over the position reporting context between the RNC and the end        user. In both cases the end user could be another application        running in the wireless terminal.-   Addition of a confidence information element to acquisition    assistance data carried over interfaces in the WCDMA radio access    network (RAN) or in the Long Term Evolution (LTE) radio access    network (RAN).

7.1 Signaling of Confidence Information: Example Embodiments

FIG. 1 shows portions of a telecommunications system including portionsof a Long Term Evolution (LTE) radio access network (RAN) useful forposition location determination. The architecture illustrated in FIG. 1includes Gateway Mobile Location Center (GMLC) 22; Mobility ManagementEntity (MME) 24; evolved Serving Mobile Location Center (eSMLC) 26; basestation or eNodeB 28; and wireless terminal (UE) 30. The Gateway MobileLocation Center (GMLC) 22 is the first node an external LocationServices client 34 accesses in a public land mobile network (PLMN). Themobility management entity (MME) is a network node which keeps theinformation in the UE context and handles, e.g., Tracking Area Update(TAU) as described in 3GPP TS 23.401. Mobility Management Entity (MME)24 communicates with Gateway Mobile Location Center (GMLC) 22 over aninterface known as the SLg interface (defined in ELP 29.172) and withevolved Serving Mobile Location Center (eSMLC) 26 over an interfaceknown as the SLs interface (defined in LCS-AP 29.171). The SLs and SLginterfaces are represented by dashed-dotted lines in FIG. 1.

FIG. 1 further illustrates employment of certain protocols bydashed-double dotted lines, such as employment of the LTE PositioningProtocol (LPP) between evolved Serving Mobile Location Center (eSMLC) 26and wireless terminal (UE) 30; employment of the LCS-AP 29.171 protocolbetween Mobility Management Entity (MME) 24 and evolved Serving MobileLocation Center (eSMLC) 26; and employment of the EPC 29.172 protocolbetween Mobility Management Entity (MME) 24 and Gateway Mobile LocationCenter (GMLC) 22. The LPP protocol is described, e.g., in LPPspecification 3GPP TS 36.355, “LTE Positioning Protocol (LPP)”,available at http://www.3gpp.org, incorporated herein by reference. TheLCS-AP 29.171 protocol is described, e.g., in 3GPP TS 29.171: “LCSApplication Protocol (LCS-AP) between the MME and E-SMLC”, available athttp://www.3gpp.org, incorporated herein by reference. The EPC protocolis described, e.g., in 3GPP TS 29.172, “Location Services (LCS); EPC LCSProtocol (ELP) between the GMLC and the MME; SLg interface”, availableat http://www.3gpp.org.

The technology disclosed herein is not limited to a Long Term Evolution(LTE) network although such is shown in FIG. 1. It should also beunderstood that in a WCDMA radio access network (RAN) the functions ofthe evolved Serving Mobile Location Center (eSMLC) node can be preformedby a radio network controller (RNC) node which connects through a radiobase station node to the wireless terminal.

As used herein, “wireless terminal(s)” or “UE” can be mobile stations oruser equipment units (UE) such as but not limited to mobile telephones(“cellular” telephones) and laptops with wireless capability, e.g.,mobile termination, and thus can be, for example, portable, pocket,hand-held, computer-included, or car-mounted mobile devices whichcommunicate voice and/or data with radio access network.

7.2 Signaling of Confidence Information: Example Methods

FIG. 2 shows message flow in the telecommunications system of FIG. 1 fora mobile terminating location request. The message flow of FIG. 2 isillustrated in the form of various acts or steps. Act 2-1 depictsexternal Location Services client 34 making a mobile terminationlocation request to Gateway Mobile Location Center (GMLC) 22. Thepurpose of the mobile termination location request is to ascertain thelocation position of wireless terminal (UE) 30.

After performing a registration authorization (depicted by act 2-2), asact 2-3 Gateway Mobile Location Center (GMLC) 22 sends the locationrequest (ELP Provide Subscriber Location Request) to Mobility ManagementEntity (MME) 24. As act 2-4 Mobility Management Entity (MME) 24 selectsan available eSMLC to serve the location request for a wirelessterminal. Further, as act 2-5, Mobility Management Entity (MME) 24forwards the location request on the SLs interface using the LCS-APprotocol as specified in 3GPP TS 29.171 (e.g., LCS-AP Location Request).As act 2-6 the chosen eSMLC (e.g., evolved Serving Mobile LocationCenter (eSMLC) 26 in FIG. 1 sends the location request to the wirelessterminal (UE) 30 using the LPP protocol as specified in 3GPP TS 36.355(e.g., LPP Request Location Information). Note that the LPP messages aretunneled through the Mobility Management Entity (MME) 24 and the basestation or eNodeB 28.

As act 2-7 the wireless terminal ascertains its position information forreporting its position back to evolved Serving Mobile Location Center(eSMLC) 26. As indicated previously, the location position informationincludes the position location parameters, including its positionparameter, its uncertainty parameter, and its confidence/probabilityparameter.

As act 2-8 measurements from the wireless terminal (UE) 30 or a locationestimate is actually sent back to evolved Serving Mobile Location Center(eSMLC) 26 using the LTE Positioning Protocol (LPP) (e.g., LPP ProvideLocation Information). If the location was not estimated by wirelessterminal (UE) 30, as indicated by optional act 2-9 evolved ServingMobile Location Center (eSMLC) 26 determines the location of wirelessterminal (UE) 30. However determined, as act 2-10 the location report(e.g., LCS-AP Location Response) is sent to Mobility Management Entity(MME) 24. As act 2-11 Mobility Management Entity (MME) 24 in turnforwards the location report (ELP Provide Subscriber Location Response)to Gateway Mobile Location Center (GMLC) 22. The Gateway Mobile LocationCenter (GMLC) 22 receives final location estimates from MobilityManagement Entity (MME) 24 on the SLg interface using the ELP protocolas specified in 3GPP TS 29.172. As act 2-12 Gateway Mobile LocationCenter (GMLC) 22 forwards the location to external Location Servicesclient 34.

Although not specifically shown in FIG. 2, it will be appreciated that anode such as the evolved Serving Mobile Location Center (eSMLC) node orthe radio network controller (RNC) can subsequently perform a re-scalingoperation regarding uncertainty parameters. The rescaling of uncertaintyparameters is described in more detail hereinafter.

7.3 Signaling of Confidence Information: Example Wireless TerminalEmbodiments

FIG. 3 illustrates an example wireless terminal 30 according to anon-limiting basic example embodiment. FIG. 3 shows wireless terminal(UE) 30 as comprising, among its other functionalities and units,communications interface 38 and position location unit 40. The positionlocation unit 40 is shown as further comprising both parameteracquisition unit 42 and parameter reporting unit 44. Among its variousconstituent units and functionalities, parameter acquisition unit 42comprises confidence acquisition unit 46 which serves, e.g., forperforming act 2-7. Act 2-7 comprises acquiring or determining theaforementioned confidence or probability parameter. The confidenceacquisition unit 46 of wireless terminal (UE) 30 determines a value forthe confidence parameter using knowledge of how the uncertainty iscomputed, e.g., if a 2D or 3D report is used. This confidence parametermay represent any appropriate value identifying, indicating, orotherwise describing the estimated probability that wireless terminal UE(30) is located within an area associated with the confidence parameter.The confidence parameter determined or ascertained by confidenceacquisition unit 46 is included, along with the position parameter andthe uncertainty parameter, in the position location report generated byparameter reporting unit 44. The position location report generated byparameter reporting unit 44 is sent as the message of act 2-8 of FIG. 2.

7.4 Signaling of Confidence Information: Example Machine PlatformEmbodiments

FIG. 4 illustrates more structural detail for certain exampleembodiments of wireless terminal (UE) 30. For example FIG. 4 illustratesthat position location unit 40 can be provided on or realized by amachine platform 48.

The machine platform 48 can take any of several forms, such as (forexample) a computer implementation platform or a hardware circuitplatform. FIG. 4 particularly shows machine platform 48 as being acomputer platform wherein logic and functionalities of position locationunit 40 are implemented by one or more computer processors orcontrollers 50 as those terms are herein expansively defined.

The terminology “platform” is a way of describing how the functionalunits of mobile station 30 can be implemented or realized by machine.One example platform 48 is a computer implementation wherein one or moreof the elements framed by the broken line, including position locationunit 40, are realized by one or more computer processors or controllers50 as those terms are herein expansively defined. The processor(s) 50execute coded instructions in order and generate non-transitory signalsto perform the various acts described herein. In such a computerimplementation the mobile station 30 can comprise, in addition to aprocessor(s), memory section 52 (which in turn can comprise randomaccess memory 54; read only memory 56; and application memory 58 (whichstores, e.g., coded instructions which can be executed by the processorto perform acts described herein); and any other memory such as cachememory, for example).

In conjunction with the computer platform FIG. 4 shows wireless terminal(UE) 30 as including various interfaces, among which are keypad 60;audio input device (e.g. microphone) 62; visual input device (e.g.,camera) 64; visual output device (e.g., display 66); and audio outputdevice (e.g., speaker) 68. Other types of input/output devices can alsobe connected to or comprise wireless terminal (UE) 30.

Another example platform suitable for wireless terminal (UE) 30 is thatof a hardware circuit, e.g., an application specific integrated circuit(ASIC) wherein circuit elements are structured and operated to performthe various acts described herein.

7.5 Signaling of Confidence Information in Difference Type Messages

It will be appreciated that the message flow of FIG. 2 is for aprocedure called Mobile Terminated Location Request. Other procedureslike Mobile Originated Location Request and Network Induced LocationRequest are also defined in the LCS standards. Messages of those otherprocedures can also include the confidence information, and theconfidence information (e.g., in the form of a confidence informationelement) can be carried in messages as needed over other interfaces suchas the LPP interface, the SLp interface, and the SLs interface.

7.6 Signaling of Confidence Information with Acquisition Assistance Data

As explained above, acquisition assistance data provides the wirelessterminal with information that allows the wireless terminal to detectthe GPS signals more quickly and allows detection of much weakersignals. It does this by providing information to the wireless terminalas to where to look for the signals. Typically, A-GPS accuracy canbecome as good as 10 meters without differential operation.

An example of an A-GPS positioning system is displayed in FIG. 5. Asshown in FIG. 5, GPS reference receivers attached to a cellularcommunication system collect assistance data that, when transmitted toGPS receivers in terminals connected to the cellular communicationsystem, enhance the performance of the GPS terminal receivers. FIG. 6shows an example serving mobile location center (SMLC) network whereinthe SMLC receives a request for assistance data for a particularwireless terminal (UE). The request effectively includes the initiallocation estimate and the uncertainty of the estimate, which is based onthe size of the serving cell. The initial location estimate and theuncertainty are used to calculate the acquisition assistance data usinginformation from a wide area reference network (WARN). This acquisitionassistance data is used to populate the message that is sent back to thenetwork and on to the wireless terminal.

FIG. 5 and FIG. 6 further show that, according to an aspect of thetechnology disclosed herein, a message including acquisition assistancedata comprises not only the initial location estimate and theuncertainty of the estimate, but also a confidence or probability valuefor the estimate.

7.7 Signaling of Confidence Information in Information Elements

According to one aspect of the technology disclosed herein, variousmessages include additional information element(s) that specify theaforementioned confidence parameter. Such messages include not onlythose in the flow of FIG. 2, but also messages that pertain toacquisition assistance data.

For example, unlike prior art practice, confidence information elementsare added to the 3GPP “polygon” and “ellipsoid point with uncertaintycircle” reporting formats that are used on the LPP interface, the SLpinterface, and the SLs interface. To reflect these aspects of thetechnology disclosed herein, FIG. 7A illustrates the “polygon” reportingformat as comprising the following information elements (among otherpossible information elements): position information element 70 andconfidence information element 74. By the size of the polygon theposition information element 70 implicitly provides the uncertaintyinformation, so that a separate information element is not needed.

Similarly, FIG. 7B illustrates the “ellipsoid point with uncertaintycircle” reporting format as comprising the following informationelements (among other possible information elements): positioninformation element 80; uncertainty information element 82; andconfidence information element 84.

FIG. 7C illustrates a message including acquisition assistance data ascomprising initial location estimate 90; the uncertainty of the estimate92; and confidence or probability value 94 for the estimate.

Table 1 appended hereto reflects (by boldface or dark font) changes thatcan be implemented to the LPP specification 3GPP TS 36.355 (incorporatedherein by reference) in order to add information elements reflected byconfidence information element 44 and confidence information element 54.

Table 2 appended hereto reflects (by boldface or dark font)changes thatcan be implemented to Table 7.4.12-1 in 3GPP TS 29.171 in order toimplement the technology disclosed herein over the SLp and SLsinterfaces. In addition, the 3GPP TS 23.032 specification also needs thecorresponding modifications of Table 2.

The aspect of the technology disclosed herein that involves adding theconfidence information (e.g., confidence information element) to thereported information affords many advantages. Example advantages includethe following:

-   Signaling means that guarantee that confidence can always be    reported from the UE to the eSMLC, for UE based A-GPS positioning in    the LTE system.-   Signaling means that guarantee that confidence can always be    reported from the UE to the eSMLC, for UE based OTDOA positioning in    the LTE system.-   Enabling of confidence scaling in the eSMLC of reported positioning    results from the UE, to comply with end user confidence    requirements, also for the shape ellipsoid point with uncertainty    circle.-   Signaling means for reporting of confidence from the eSMLC to the    end user for UE based A-GPS and UE-based OTDOA positioning, using    the ellipsoid point with uncertainty circle format.-   Signaling means for reporting of confidence from the end user for    the cell ID and AECID positioning methods.

8.0 Parameter Scaling 8.1 Reasons for Parameter Scaling

Another aspect of the technology disclosed herein addresses, e.g.,conventional problems caused by too vague requirements and signaling ofwhat “positioning accuracy” means. As mentioned above, accuracy in theradio navigation field, in particular for A-GPS, is a random quantity.This means that any time a position uncertainty is determined, theuncertainty should be accompanied with a corresponding “probability” (or“confidence”) that the terminal is actually in the region defined by thereported position and the reported uncertainty. In the 3GPP WCDMAspecification uncertainty can be expressed in terms of an uncertaintycircle, an uncertainty ellipse and an uncertainty ellipsoid. See, e.g.,3GPP, TS 23.032, “Universal Geographical Area Description (GAD)”,available at http://www.3gpp.org.

A problem affecting A-GPS addressed by this aspect of the technologydisclosed herein originates from the following facts:

Fact 1. The 3GPP standard does not specify exactly how the uncertaintyand the probability (also known as the confidence) are related.Typically this would require a specification stating how the confidencevalue shall be related to the covariance matrix of the uncertaintymeasure. In particular, this would require a different handling of2-dimensional and 3-dimensional uncertainty.

Fact 2: Uncertainty criteria, such as requested horizontal and verticalaccuracies, that is received in a node (such as the RAN or eSMLC) fromthe core network (and thus from the end user) do not specify theconfidence for which the quality of service (QoS) request is valid.

Fact 3: The uncertainty criteria (horizontal and vertical accuracies)that is transmitted from a node (such as the RNC or the eSMLC) to theterminal to specify the requested accuracy of the measured A-GPS resultare not accompanied by a confidence value.

Fact 4: The A-GPS result reported from the terminal to a node (such asthe RNC or eSMLC) normally contains an uncertainty parameter (e.g. inthe form of at least horizontal accuracy and most often also a verticalaccuracy) and a corresponding confidence value.

Fact 5: Shape conversions are applied in the RNC of the WCDMA RAN or inthe eSMLC of the LTE RAN in order, e.g., to scale the accuraciesaccording to operator configured confidence values for reporting ofpositioning results.

As understood from the foregoing, when a node (such as the RNC of theWCDMA RAN or the eSMLC of the LTE RAN) provides the wireless terminalwith requested accuracy information, the node neither knows nor cansignal a correct confidence value to the terminal As a consequence theaction in systems known in prior art has been to forward the incominguncertainty criteria (in the form of horizontal and vertical accuracyrequirements) to the wireless terminal unaffected. Then the wirelessterminal tries to provide a result according to the request. However,the result provided by the wireless terminal is provided at theconfidence level selected by the specific wireless terminal type, notnecessarily at the confidence level really needed by the end user.Therefore, the node (e.g., RNC of the WCDMA RAN or eSLMC of the LTE RAN)may perform a shape conversion to scale the obtained uncertaintyparameter (e.g., the horizontal and vertical accuracies) to the levelthat is configured for the specific service (e.g. as directed by theClient Type IE).

As an example of the foregoing, it may then happen that the wirelessterminal provides a result, exactly at the received requested accuracylevel, with the accuracy requested, and at a confidence level oftypically 39% or 20% (2D and 3D covariance matrix level, respectively).However, in case of North American emergency positioning 95% confidenceis required for reporting. Hence in this case the node (RNC or eSMLC)would scale up the obtained uncertainty parameter (e.g., horizontal andvertical accuracies). Such scaling up would result in a failure to meetthe requested accuracies that were originally received from the corenetwork and the end user. The fact that the QoS was not fulfilled mayalso be signaled to the end user, and it may also affect performancemanagement counters. Both of these result in statistics that may in theend be reported to the US Federal Communication Commission (FCC) withthe result that the operator's fulfillment of the regulatory E-911requirements may be in question.

8.2 Overview of Parameter Scaling

In view of the foregoing, an aspect of the technology disclosed hereintherefore concerns a scaling technique and algorithm that scales theuncertainty criteria originally received from the end user before theuncertainty criteria is sent on to the wireless terminal as requirementson the accuracy of A-GPS positioning performed by/for the wirelessterminal. In an example embodiment the amount/degree of scaling isselected according to a configured best estimate of the confidence anduncertainty relation, and such best estimate can be based on themajority of the terminals of the network. The scaling also accounts forthe type of service, e.g., as signaled by the Client Type IE in theWCDMA RANAP LOCATION REPORTING CONTROL message.

The technology disclosed herein thus performs and features a new scalingof position uncertainty criteria that is received from the end user.Position uncertainty criteria may represent any appropriate informationindicating an accuracy, precision, certainty, or uncertainty that isdesired, required, or expected by the requesting component, such ashorizontal and vertical inaccuracies requested by the end user. Positionuncertainty criteria may represent or indicate a specific value, a rangeof values, a maximum or minimum threshold, a category (e.g., “highaccuracy”), or other information describing the relevant accuracy,precision, certainty, or uncertainty.

For a WCDMA RAN, for example, the position uncertainty criteria can bereceived over the RANAP interface between the RNC and the core network.For a WCDMA RAN case the scaling can be performed in the RNC; for an LTERAN case the scaling can be performed in the evolved Serving MobileLocation Center (eSMLC) node. In another case the scaling canalternatively be performed in the wireless terminal itself. In all suchcases the scaling transforms the requested inaccuracies (e.g., theposition uncertainty criteria) in accordance with (e.g., to beconsistent with) the confidence values that are reported by theterminals (or configured best estimates of those confidence values). Thewireless terminal's confidence values can be, e.g. 39% in a twodimensional (2D) case and 20% in a three dimensional (3D) case. Forexample, for emergency positioning this would mean that the horizontaland vertical inaccuracy would be scaled down. The wireless terminalwould then determine the A-GPS position (position parameter),uncertainty parameter, and confidence parameter. A shape conversion isthen performed to re-scale up the reported uncertainty to correspond tothe confidence value needed for reporting. In some cases the parametersare sent to a node (e.g., the RNC or the eSMLC) and the node performsthe shape conversion. In other cases the wireless terminal itself canperform the shape conversion/re-scaling. In view of the scaling andsubsequent re-scaling of the technology disclosed herein the quality ofservice can be met.

Advantages of this aspect of technology disclosed herein include anenhanced accuracy as well as a reduced risk for the requested QoS notbeing fulfilled.

8.3 Example Embodiments 8.3.1 Generic Embodiments

Thus, an aspect the technology disclosed herein generally concernsnetwork devices and methods which implement parameter scaling inconjunction with a position determination operation or procedure. FIG. 8depicts a representative, generic network device 100 which implementsparameter scaling. Device 100 comprises communication interface 104 andscaler 106. As described hereinafter, in some embodiments the device 100can be a node, such as a radio network controller (RNC) or an evolvedServing Mobile Location Center (eSMLC) node. In other exampleembodiments the device 100 can be the very wireless terminal whoseposition is to be determined.

FIG. 9 illustrates representative, non-limiting acts or steps involvedin a generic position determination method involving parameter scaling.Act 9-1 of the general method of FIG. 9 comprises the device 100receiving (via communication interface 104) a position request message108 (depicted by an arrow in FIG. 8). The position request message 108may represent a message, a packet, a signal, or information structuredand communicated in any other appropriate manner that requestsdetermination of a position of a particular wireless terminal. Theposition request message 108 includes position uncertainty criteria andoptionally includes confidence criteria for the position report whichthe wireless terminal is expected to return to the network. Theconfidence criteria is said to be optionally included since, in someembodiments, the confidence criteria can be included in the positionrequest message but, in other embodiments (as in the case of WCDMA) canbe configured in the communications device or received from anotherelement of the system. In many situations, if not most situations, theconfidence criteria is in a neighborhood of about 90% or greater. On theother hand, device 100 may know or at least anticipate that theconfidence parameter that the wireless terminal will eventuallysend/return in its position report—the confidence reportingcharacteristic of the wireless terminal—will instead be significantlyless. The device 100 may have knowledge of, or intelligently guess orestimate, the confidence parameter based on configured information, pasthistory or other information which can be stored in or obtained fromconfidence anticipator 110. For example, the wireless terminal mayreturn a confidence parameter of about 39% for a two dimensional case ora 20% confidence parameter for a three dimensional case.

Act 9-2 comprises the device 100 determining that a confidencedifferential exists between a confidence reporting characteristic of thewireless terminal and the confidence criteria. For example, for thethree dimensional case the device 100 may determine a confidencedifferential of about 70% (e.g., 90%-20%).

As a result of the existence and determination confidence differential,act 9-3 comprises the device 100 scaling the position uncertaintycriteria to obtain a scaled position uncertainty criteria for use by thewireless terminal. In particular, the scaler 106 is configured to scalethe position uncertainty criteria to obtain the scaled positionuncertainty criteria. Example scaling techniques are describedhereinafter. For example, in an example implementation scaler 106 canscale the position uncertainty criteria in accordance with (e.g., inproportion or pre-set relation to) the confidence differential to obtainthe scaled position uncertainty criteria. In general, the scalingtransforms the requested inaccuracies (e.g., the position uncertaintycriteria) in accordance with (e.g., to be consistent with) configuredbest estimates of the confidence values that are to be (or expected tobe) reported by the terminals.

8.3.2 Scaling at Node Embodiments

FIG. 10 generically illustrates example embodiments in which device100(10) can be a node (e.g. network node) such as a radio networkcontroller (RNC) or an evolved Serving Mobile Location Center (eSMLC)node. FIG. 10 shows the device 100(10) comprising two communicationsinterfaces, including interface 104U through which communication occurswith, e.g., a client who requests the position determination of thewireless terminal, and interface 104D through which device 100(10)communicates (at least ultimately) with the wireless terminal.

FIG. 10 further shows device 100(10) as comprising position locationunit 112. The position location unit 112 comprises scaler 106, re-scaler114, and various message handlers and reformatters. For example,position location unit 112 comprises request handler 116, requestreformatter 118; report handler 120, and report reformatter 122.

FIG. 11 illustrates representative, non-limiting acts or steps involvedin a position determination method involving parameter re-scaling whichcan be performed by a node such as that of device 100(10), andparticularly by position location unit 112. The first three acts of themethod of FIG. 11 resemble those of the generic method of FIG. 9 andhence are not described in detail. In this regard, act 11-1 comprisesthe device 100(10) receiving (via communication interface 104U) theposition request message 108, which is processed by request handler 116.Act 11-2 comprises the position location unit 112 determining that theaforementioned confidence differential exists between a confidencereporting characteristic of the wireless terminal and the confidencecriteria. Act 11-3 comprises the scaler 106 scaling the positionuncertainty criteria to obtain scaled position uncertainty criteria foruse by the wireless terminal

Further acts of the node-performed method of FIG. 11 include act 11-4through act 11-6. Act 11-4 comprises the request reformatter 118preparing and the communication interface 104D transmitting the scaledposition uncertainty criteria (e.g., scaled horizontal and verticalinaccuracies) to the wireless terminal. The scaled position uncertaintycriteria can be included in reformatted position request message 124.The reformatted position request message 124 can resemble the positionrequest message 108, but includes the scaled position uncertaintycriteria rather than the original position uncertainty criteria asreceived in position request message 108.

In response to the reformatted position request message 124, thewireless terminal performs a procedure in which the wireless terminaldetermines or is apprised of its location/position. The procedure canbe, for example, an A-GPS procedure or an A-GPS facilitated procedure.In conjunction with execution of the position determining procedure thewireless terminal sends a position report 126 to device 100(3). For thereported wireless terminal the position report 126 typically includesinformation comprising, e.g., a reported position, a reported positionuncertainty parameter, and a reported confidence parameter. The positionreport 126 is also known as the scaled position report 126 since thereported position uncertainty parameter is based on the scaled positionuncertainty criteria. The reported confidence parameter of the positionreport 126 is based on the confidence reporting characteristic of thewireless terminal.

Act 11-5 comprises the device 100(10) receiving and the report handler120 thereof processing the position report 126 from the wirelessterminal. Act 11-6 comprises the re-scaler 114 re-scaling the reportedposition uncertainty parameter in a manner so that the positionuncertainty criteria is satisfied. For example, in an exampleimplementation the method further comprises re-scaling the reportedposition uncertainty parameter in accordance with (e.g., in proportionor pre-set relation to) the confidence differential. In other words,re-scaler 114 performs a shape conversion to re-scale up the reporteduncertainty to correspond to the confidence value needed for reporting(e.g., the confidence criteria).

After the re-scaling of act 11-6 the device 100(10) sends re-scaledposition report 128 to its client. The re-scaled position report 128 isprepared by report reformatter 122 and sent via communication interface104U to the client. The re-scaled position report 128 includes thereported position, the re-scaled reported position uncertaintyparameter, and the reported confidence parameter.

As understood from the foregoing, the device 100(10) receives theposition uncertainty criteria and the confidence criteria in positionrequest message 108. The device 100(10) makes an estimate or projectionof the confidence parameter that the wireless terminal will report inconnection with its 126. In other words, (as act 11-02) the device100(10) determines or retrieves the confidence reporting characteristicof the wireless terminal. For example, the confidence criteria fordetermining the position the wireless terminal may be 95%, but thedevice 100(10) may guess or know (via confidence anticipator 110) thatthe wireless terminal will respond to it with a 39% confidence. If thedevice 100(10) were merely to download the required uncertainty criteriato the wireless terminal, the wireless terminal would (in conventionalmanner) provide the device 100(10) with its position parameter and itsuncertainty parameter with the confidence reporting characteristic ofthe wireless terminal. If the device were then to scale up theuncertainty parameter in view of the mismatch between the confidencecriteria and the confidence reporting characteristic of the wirelessterminal, the initially requested quality of service may not besatisfied.

In order to avoid the foregoing, as act 11-03 the device 100(10) scales(e.g., scales down) the position uncertainty criteria (e.g., thehorizontal and vertical inaccuracies) and downloads a scaled positionuncertainty criteria to the wireless terminal. The device 100(10)thereafter receives (as act 11-5) the position report 126 from thewireless terminal with its reported uncertainty parameter and aconfidence reporting characteristic of, for example, 39% confidence (forthe two dimensional case). As act 11-6 the re-scaler 114 (re)scales(e.g., scales up) the reported uncertainty parameter to correspond to aconfidence of 95%, so that the requesting client obtains essentiallyexactly the position and accuracy (uncertainty) that the clientrequires.

8.3.3 Scaling at Wireless Terminal Embodiments

FIG. 12 generically illustrates example embodiments in which device100(12) can be the very wireless terminal whose position is beingsought. FIG. 12 shows the device 100(12) as comprising communicationsinterface 104(12) and position location unit 112(12). The wirelessterminal 100(5) communicates through communication interface 104(12)over a radio or air interface to a radio access network, e.g., to aradio base station node or an eNodeB, for example. FIG. 12 further showsposition location unit 112(5) as comprising scaler 106(12), confidencedetermination unit 110(12), re-scaler 114(12), request handler 116(12),report formatter 122(12), and position location controller 130. Asexplained below, the wireless terminal 100(12) is configured to use thescaled position uncertainty criteria in a position determinationprocedure (e.g., A-GPS procedure) to determine a position parameter, aposition uncertainty parameter, and a confidence parameter. The scaledposition uncertainty criteria is used the input for the A-GPS positiondetermination since, e.g., the terminal will try and meet the scaleduncertainty criteria (it may, e.g., continue longer if this criterion ismore difficult to meet). Stated differently, the reported positionuncertainty parameter is determined as a function of the scaled positionuncertainty criteria. The position uncertainty parameter which is outputfrom the A-GPS determination can be but need not necessarily be the sameas the scaled position uncertainty criteria (e.g., it may be less thanor equal or larger.)

FIG. 13 illustrates representative, non-limiting acts or steps involvedin a position determination method involving parameter re-scaling whichcan be performed by a wireless terminal such as wireless terminal100(12), and particularly by position location unit 112(12). The firstthree acts (act 13-1 through act 13-3) of the method of FIG. 12 resemblethose of the generic method of FIG. 9 and hence are not described indetail, it being understood however that act 13-1 through 13-3 areperformed at the wireless terminal 100(12) rather than at a networknode. In this regard, act 13-1 comprises the wireless terminal 100(12)receiving (via communication interface 104(12)) the position requestmessage 108(12), which is processed by request handler 116(12). Act 13-2comprises the position location unit 112(12) determining that theaforementioned confidence differential exists between a confidencereporting characteristic of the wireless terminal and the confidencecriteria. Act 13-3 comprises the scaler 106(12) scaling the positionuncertainty criteria to obtain scaled position uncertainty criteria foruse by the wireless terminal 100(12).

Act 13-4 of FIG. 13 comprises the position location unit 112(12)performing or participating in a position determination procedure and,as a result, determining at least a position parameter and a positionuncertainty parameter as a function of the scaled position uncertaintycriteria. Act 13-4 can comprise the position location unit 112(12) usingthe scaled position uncertainty criteria to determine a positionparameter, a position uncertainty parameter, and a confidence parameter.The scaled position uncertainty criteria is used the input for the A-GPSposition determination since, e.g., the terminal will try and meet thescaled uncertainty criteria (it may, e.g., continue longer if thiscriterion is more difficult to meet). The position uncertainty parameterwhich is output from the A-GPS determination can be but need notnecessarily be the same as the scaled position uncertainty criteria(e.g., it may be less than or equal or larger.) Act 13-5 comprises theposition location unit 112(12) of wireless terminal 100(12) re-scalingthe position uncertainty parameter to form a re-scaled uncertaintyparameter that satisfies the position uncertainty criteria. For example,in an example implementation the act 13-5 comprises re-scaling thereported position uncertainty parameter in accordance with (e.g., inproportion or pre-set relation to) the confidence differential. Act 13-6comprises the wireless terminal 100(12) generating a position report(e.g., re-scaled position report 128) comprising the position parameter,the re-scaled uncertainty parameter, and the confidence parameter. Theposition report is generated, e.g., by report reformatter 122(12). Theposition report 128(12) is then sent to across the air or radiointerface (via communication interface 104(12)) to the node thatrequested the position of the wireless terminal 100(12)).

8.3.3.1 Confidence for Certain Reporting Formats

In an example implementation, the wireless terminal is configured togenerate the position report 128(12) in which a reported position of thewireless terminal is expressed in a polygon report format. The polygonreport format includes an information element comprising the reportedconfidence parameter, as illustrated by confidence information element74 of FIG. 7A. In another example implementation, the wireless terminalis configured to generate the position report 128(12) in which areported position of the wireless terminal is expressed in an ellipsoidpoint with uncertainty circle report format. The ellipsoid point withuncertainty circle report format includes an information elementcomprising the reported confidence parameter, as illustrated byconfidence information element 84 of FIG. 7B.

8.3.4 Machine Platform Embodiments

In some implementations various units or functionalities of devices 100of each of the example embodiments described herein, including theposition location unit and its constituent components, can be providedon or realized by a machine platform 148. As explained previously, theterminology “platform” is a way of describing how the functional unitsof device 100, device 100(10), and/or device 100(12) can be implementedor realized by machine For this reason FIG. 8, FIG. 10, and FIG. 12depict by broken lines the machine platform 148 as being implemented byone or more computer processors or controllers 150 as those terms areherein expansively defined. The processor(s) 150 can execute codedinstructions in order and generate non-transitory signals to perform thevarious acts described herein. In such a computer implementation thedevice 100, device 100(10), and/or device 100(12) can comprise, inaddition to a processor(s), memory section 152 (which in turn cancomprise random access memory 154; read only memory 156; and applicationmemory 158 (which stores, e.g., coded instructions which can be executedby the processor to perform acts described herein); and any other memorysuch as cache memory, for example). The device 100, device 100(10),and/or device 100(12) can also include various interfaces, such as akeypad; an audio input device (e.g. microphone); a visual input device(e.g., camera); visual output device (e.g., a display); and an audiooutput device (e.g., speaker). Other types of input/output devices canalso be connected to or comprise the device 100, device 100(10), and/ordevice 100(12).

Another example platform suitable for the device 100, device 100(10),and/or device 100(12) is that of a hardware circuit, e.g., anapplication specific integrated circuit (ASIC) wherein circuit elementsare structured and operated to perform the various acts describedherein.

8.4 Scaling Techniques

As indicated above, in the various example embodiments the scaler 106serves to scale the position uncertainty criteria (e.g., horizontal andvertical inaccuracies) to obtain the scaled position uncertaintycriteria. For example, in an example implementation scaler 106 can scalethe position uncertainty criteria in accordance with (e.g., inproportion or pre-set relation to) the confidence differential to obtainthe scaled position uncertainty criteria. In general, the scalingtransforms the requested inaccuracies (e.g., the position uncertaintycriteria) in accordance with (e.g., to be consistent with) configuredbest estimates of the confidence values that are to be (or expected tobe) reported by the terminals. Example scaling techniques are describedbelow.

8.4.1 Two Dimensional Scaling Techniques

For scaling of the position uncertainty criteria in the two dimensionalcase the scaling is performed on the radius of an uncertainty circle. Toderive the scaling, an uncertainty region determined by an ellipse isfirst used, then the circular uncertainty scaling is obtained as aspecial case by setting the semi-major axis of the ellipse equal to thesemi-minor axis of the ellipse. The present discussion assumes that theuncertainty codes (e.g., the position uncertainty criteria), which insome example embodiments can be received over the RANAP interface (inthe UMTS case), has been transformed to a horizontal (in)accuracy and avertical (in)accuracy, respectively.

The result of an A-GPS report is associated with a Gaussian random errorassumption. This follows since the time errors that give the ranges tothe satellites can be assumed to be identically distributed. Afterlinearizing the measurement equations, the strong law of large numberscan be applied to arrive at the conclusion that the error distributionis Gaussian.

The ellipse is parameterized with semi-major axis a′, semi-minor axis b′and an angle φ relative to north, counted clockwise from the semi-majoraxis, as shown in FIG. 14. For symmetry reasons that the angle φ doesnot affect the final result. The value of φ is therefore taken to be 0for the calculations below. The goal is hence to convert the ellipsoidconfidence area at confidence level C_(Initial) to a circular confidencearea at confidence level C_(Required)).

In order to proceed, a′ and b′ are then transformed into the standarddeviations of a normal distribution. This is done using the followingcalculations, where v is the scale factor that translates from onestandard deviation to C_(Initial)

$\begin{matrix}{C_{Initial} = {\underset{{\frac{x^{\prime \; 2}}{a^{\prime \; 2}} + \frac{y^{\prime \; 2}}{b^{\prime 2}}} \leq 1}{\int\int}\frac{1}{2{\pi \left( {va}^{\prime} \right)}\left( {vb}^{\prime} \right)}^{{- \frac{1}{2}}{({x^{\prime}\mspace{14mu} y^{\prime}})}{(\begin{matrix}{({va}^{\prime})}^{2} & 0 \\0 & {({vb}^{\prime})}^{2}\end{matrix})}^{- 1}{(\begin{matrix}x^{\prime} \\y^{\prime}\end{matrix})}}{x^{\prime}}{y^{\prime}}}} \\{= {\underset{{x^{\prime 2} + y^{\prime \; 2}} \leq 1}{\int\int}\frac{1}{2{\pi \left( {va}^{\prime} \right)}\left( {vb}^{\prime} \right)}^{{- \frac{1}{2}}{(\begin{matrix}{va}^{\prime} & {yb}^{\prime}\end{matrix})}^{T}{(\begin{matrix}{({va}^{\prime})}^{2} & 0 \\0 & {({vb}^{\prime})}^{2}\end{matrix})}^{- 1}{(\begin{matrix}{xa}^{\prime} \\{yb}^{\prime}\end{matrix})}}}} \\{\left| \begin{matrix}a^{\prime} & 0 \\0 & b^{\prime}\end{matrix} \middle| {{x}{y}} \right.} \\{= {\frac{1}{2\pi}{\int_{0}^{2\pi}{\int_{0}^{1}{\frac{1}{v^{2}}^{{- \frac{1}{2v^{2}}}r^{2}}r{r}{Ϛ}}}}}} \\{{= {1 - ^{- \frac{1}{2v^{2}}}}},}\end{matrix}$

From the foregoing the transformations to semi-major and semi-minor axescorresponding to a unit standard deviation follow as:

a=a′/√{square root over (−2 ln(1−C _(initial)))}

b=b′/√{square root over (−2 ln(1−C _(initial)))}

Next, to obtain the scaling, the following expression is evaluated tocompute or determine the uncertainty radius r′ at the two dimensionalcovariance matrix level:

r=r′/√{square root over (−2 ln(1−C _(initial)))}.

The above equations correspond to a confidence value of about 39%. Theexample calculation involves no scaling, v=1, and thus the expression1−exp(−0.5)=0.39.

In case another scaled confidence value (e.g., another uncertaintyradius r″) is required, the last equation can be used backwards tocompute the sought quantity, i.e.,

r″=r′√{square root over (−2 ln(1−C _(prescale)))}.

In other words, the equations above take a 95% uncertainty value down toa “guessed” 2 0 39% value, which is the “guess” of what the terminaldoes. In case it is desired to take a 95% uncertainty value down to a45% guessed value, for example, the 95% uncertainty value can first betaken down to 39%, then applied backwards (changing division tomultiplication and changing the confidence value in the formula).

8.4.2 Three Dimensional Scaling Techniques

scaling for the three dimensional (3D) case parallels the twodimensional case (2D) in that a Gaussian 3D distribution is assumed andan ellipsoid is first considered, assuming the third principal axisbeing equal to the vertical inaccuracy (e.g., a vertical component ofthe position uncertainty criteria).

This transformation for the 3D case builds on the transformation of theprevious sub-section for the 2D case. Care needs to be exercised sincethe transformation from 3D confidence values to a 3D unit covariance isdifferent than in the 2D case. It is only at unit covariance confidencelevel that it is possible to extract the 2D covariance matrix of theellipse from the 3D ellipsoid, and proceed as above. In order to derivethe required relation, the calculations of the previous section for the2D case replaced by the following calculations:

$\begin{matrix}{C_{Initial} = {\underset{{\frac{x^{\prime \; 2}}{a^{\prime \; 2}} + \frac{y^{\prime \; 2}}{b^{\prime \; 2}} + \frac{z^{\prime \; 2}}{c^{\prime \; 2}}} \leq 1}{\int{\int\int}}\frac{1}{\left( {2\pi} \right)^{1.5}a^{\prime}b^{\prime}c^{\prime}v^{3}}^{{- \frac{1}{2v^{2}}}{({\frac{x^{\prime \; 2}}{a^{\prime \; 2}} + \frac{y^{\prime \; 2}}{b^{\prime \; 2}} + \frac{z^{\prime \; 2}}{c^{\prime \; 2}}})}}{x^{\prime}}{y^{\prime}}{z^{\prime}}}} \\{= {\underset{{x^{2} + y^{2} + z^{2}} \leq 1}{\int{\int\int}}\frac{1}{\left( {2\pi} \right)^{1.5}v^{3}}^{{- \frac{1}{2v^{2}}}{({x^{\prime} + y^{2} + z^{2}})}}{x}{y}{z}}} \\{= {\int_{0}^{2\pi}{\int_{- \frac{\pi}{2}}^{\frac{\pi}{2}}{\int_{0}^{1}{\frac{1}{\left( {2\pi} \right)^{1.5}}r^{2}{\cos (\psi)}^{{- \frac{1}{2v^{2}}}r^{2}}{r}{\psi}{\xi}}}}}} \\{{= {{{erf}\left( \frac{1}{\sqrt{2}v} \right)} - {\frac{1}{v}\sqrt{\frac{2}{\pi}}^{- \frac{1}{2v^{2}}}}}},}\end{matrix}$

In the preceding calculation c′ denotes the vertical inaccuracy. Theobtained equation can be solved numerically for a set of givenC_(Initial), resulting in a corresponding set of v, generating a tableas exemplified by Table 3. Table 3 shows confidence values (fractions)and scale factors in the 3D case. In particular, Table 3 gives v forgiven C_(Initial), from which the unit covariance ellipsoid axes followas a=va′, b=vb′ and c=vc′. In order to obtain a high accuracyinterpolation is utilized in the table. Also in this case, a backwardinterpolation can be used to compute scale factors other than for theunit covariance level.

8.4.3 One Dimensional Scaling Techniques

For the one dimensional scaling case the one dimensional (1D) Gaussiandistribution is used for scaling corresponding to 68%. The case isapplicable in the exceptional case were only vertical inaccuracy ispre-scaled. Example calculations for the 1D are as follows:

$\begin{matrix}{C_{Initial} = {\int_{- r}^{r}{\frac{1}{\sqrt{2\pi}{vr}}^{- \frac{1x^{\prime \; 2}}{2v^{2}r^{2}}}{x^{\prime}}}}} \\{= {\frac{1}{\sqrt{2\pi}v}{\int_{- 1}^{1}{^{- \frac{1x^{2}}{2v^{2}}}{x}}}}} \\{= {{erf}\left( \frac{1}{\sqrt{2}v} \right)}}\end{matrix}$

The preceding equation cannot be solved analytically. Hence for the onedimensional case the solution can involve using a table such as Table 4.Table 4 thus shows confidence values (fractions) and scale factors inthe 1D case.

Although the description above contains many specificities, these shouldnot be construed as limiting the scope of the invention but as merelyproviding illustrations of some of the presently preferred embodimentsof this invention. Thus the scope of this invention should be determinedby the appended claims and their legal equivalents. Therefore, it willbe appreciated that the scope of the present invention fully encompassesother embodiments which may become obvious to those skilled in the art,and that the scope of the present invention is accordingly to be limitedby nothing other than the appended claims, in which reference to anelement in the singular is not intended to mean “one and only one”unless explicitly so stated, but rather “one or more.” All structural,chemical, and functional equivalents to the elements of theabove-described preferred embodiment that are known to those of ordinaryskill in the art are expressly incorporated herein by reference and areintended to be encompassed by the present claims. Moreover, it is notnecessary for a device or method to address each and every problemsought to be solved by the present invention, for it to be encompassedby the present claims. Furthermore, no element, component, or methodstep in the present disclosure is intended to be dedicated to the publicregardless of whether the element, component, or method step isexplicitly recited in the claims. No claim element herein is to beconstrued under the provisions of 35 U.S.C. 112, sixth paragraph, unlessthe element is expressly recited using the phrase “means for.”

TABLE 1 EllipsoidPointWithUncertaintyCircle ::= SEQUENCE { latitudeSignLatitudeSign, degreesLatitude DegreesLatitude, degreesLongitudeDegreesLongitude, uncertainty Uncertainty, confidence Confidence }Polygon ::= SEQUENCE { polygonSequence PolygonSequence, confidence Confidence } PolygonSequence ::= SEQUENCE (SIZE (3..15)) OFPolygonPoints PolygonPoints ::= SEQUENCE { latitudeSign LatitudeSign,degreesLatitude DegreesLatitude, degreesLongitude DegreesLongitude }

TABLE 2 IE type and IE/Group Name Presence Range reference Semanticsdescription CHOICE Geographical Area >Point Ellipsoidpoint >>Geographical M 7.4.23 Coordinates >Point With UncertaintyEllipsoid point with uncertainty circle >>Geographical M 7.4.23Coordinates >>Uncertainty Code M INTEGER The uncertainty “r” (0 . . .127) expressed in meters is derived from the “Uncertainty Code” k by r =10 × (1.1^(k) − 1) >>Confidence M INTEGER In percentage (0 . . .100) >Polygon List of Ellipsoid points >>Polygon 1 . . .<maxnoofPoints> >>>Geographical M 7.4.23 Coordinates >>Confidence MINTEGER In percentage (0 . . .100) >Ellipsoid point with uncertaintyEllipse >>Geographical M 7.4.23 Coordinates >>Uncertainty Ellipse M7.4.24 >>Confidence M INTEGER In percentage (0 . . . 100) >Ellipsoidpoint with Altitude >>Geographical M 7.4.23 Coordinates >>Altitude anddirection M 7.4.22 >Ellipsoid point with altitude and uncertaintyEllipsoid >>Geographical M 7.4.23 Coordinates >>Altitude and direction M7.4.22 >>Uncertainty Ellipse M 7.4.24 >>Uncertainty Altitude M INTEGERThe uncertainty altitude (0 . . . 127) “h” expressed in metres isderived from the “Uncertainty Altitude” k, by: h = 45 × (1.025^(k)− 1) >>Confidence M INTEGER In percentage (0 . . . 100) >EllipsoidArc >>Geographical M 7.4.23 Coordinates >>Inner radius M INTEGER Therelation between the (0 . . . 2¹⁶ − 1) value (N) and the radius (r) inmeters it describes is 5N ≦ r < 5(N + 1), except for N = 2¹⁶ − 1 forwhich the range is extended to include all grater values of(r). >>Uncertainty radius M INTEGER The uncertainty “r” is (0 . . . 127)derived from the “Uncertainty radius” k by r = 10 × (1.1^(k)− 1) >>Offset angle M INTEGER The relation between the (0 . . . 179)value (N) and the angle (a) in degrees it describes is 2N ≦ a <2(N + 1) >>Included angle M INTEGER The relation between the (0 . . .179) value (N) and the angle (a) in degrees it describes is 2N < a ≦2(N + 1) >>Confidence M INTEGER (0 . . . 100)

TABLE 3 confidence values (fractions) and scale factors in the 3D caseC_(Initial) v 0.9989 0.2500 0.9947 0.2806 0.9821 0.3150 0.9540 0.35360.9042 0.3969 0.8311 0.4454 0.7385 0.5000 0.6345 0.5612 0.5283 0.63000.4276 0.7071 0.3378 0.7937 0.2613 0.8909 0.1987 1.0000 0.1490 1.12250.1105 1.2599 0.0811 1.4142 0.0591 1.5874 0.0428 1.7818 0.0309 2.00000.0222 2.2449 0.0159 2.5198 0.0113 2.8284 0.0081 3.1748 0.0057 3.56360.0041 4.0000

TABLE 4 confidence values (fractions) and scale factors in the ID caseC_(Initial) v 0.9957 0.3500 0.9760 0.4430 0.9255 0.5607 0.8412 0.70970.7344 0.8982 0.6209 1.1369 0.5129 1.4390 0.4170 1.8213 0.3356 2.30520.2682 2.9177 0.2134 3.6929 0.1694 4.6742 0.1342 5.9161 0.1062 7.48800.0840 9.4775 0.0664 11.9957 0.0525 15.1829 0.0415 19.2170 0.032824.3230 0.0259 30.7856 0.0205 38.9653 0.0162 49.3183 0.0128 62.42220.0101 79.0077 0.0080 100.0000

1. A communications device, comprising: electronic circuitry configured to: receive a position request message requesting determination of a position of a wireless terminal, the position request message including a position uncertainty criteria; determine whether a confidence differential exists between a confidence reporting characteristic of the wireless terminal and a confidence criteria known to the communications device; as a result of determining that a confidence differential exists, scale the position uncertainty criteria to obtain a scaled position uncertainty criteria for use by the wireless terminal
 2. The communications device of claim 1, wherein the confidence criteria is either included in the position request message or configured in the communications device.
 3. The communications device of claim 1, wherein the communications device is configured to scale the position uncertainty criteria in accordance with the confidence differential to obtain the scaled position uncertainty criteria.
 4. The communications device of claim 1, wherein the device is configured to receive from the wireless terminal information comprising a reported position uncertainty parameter and a reported confidence parameter, and to re-scale the reported position uncertainty parameter as a result of the confidence differential in a manner so that the position uncertainty criteria is satisfied, the reported position uncertainty parameter being based on the scaled position uncertainty criteria and the reported confidence parameter being based on the confidence reporting characteristic of the wireless terminal.
 5. The communications device of claim 4, wherein the communications device is configured to re-scale the reported position uncertainty parameter in accordance with the confidence differential.
 6. The communications device of claim 4, wherein the communications device comprises a radio network controller (RNC) node.
 7. The communications device of claim 4, wherein the communications device comprises an evolved Serving Mobile Location Center (eSMLC) node.
 8. The communications device of claim 1, wherein the device is the wireless terminal, and wherein the wireless terminal is configured to: use the scaled position uncertainty to determine a position parameter, a position uncertainty parameter, and a confidence parameter; re-scale the reported position uncertainty parameter to form a re-scaled uncertainty parameter that satisfies the position uncertainty criteria; and generate a position report comprising the position parameter, the re-scaled uncertainty parameter, and the confidence parameter.
 9. The communications device of claim 8, wherein the device is configured to use the scaled position uncertainty criteria as a reported position uncertainty parameter, and to re-scale the reported position uncertainty parameter as a result of the confidence differential in a manner so that the position uncertainty criteria is satisfied.
 10. The communications device of claim 8, wherein the wireless terminal is configured to generate a position report wherein the position parameter is expressed in a polygon report format, and wherein the polygon report format includes an information element comprising the reported confidence parameter.
 11. The communications device of claim 8, wherein the wireless terminal is configured to generate the position report wherein the position parameter is expressed in an ellipsoid point with uncertainty circle report format, and wherein the ellipsoid point with uncertainty circle report format includes an information element comprising the reported confidence parameter.
 12. The communications device of claim 1, comprising a computer-implemented scaler configured to scale the position uncertainty criteria to obtain the scaled position uncertainty criteria for use by the wireless terminal.
 13. A method of operating a communications network comprising: receiving at a network device a position request message configured to request determination of a position of a wireless terminal, the position request message including a position uncertainty criteria; determining that a confidence differential exists between a confidence reporting characteristic of the wireless terminal and a confidence criteria known to the network device; and, as a result of the confidence differential; scaling the position uncertainty criteria to obtain a scaled position uncertainty criteria for use by the wireless terminal.
 14. The method of claim 13, further comprising at least one of obtaining the confidence criteria either from the position request message and reading the confidence criteria from a memory of the network device.
 15. The method of claim 13, further comprising scaling the position uncertainty criteria in accordance with the confidence differential to obtain the scaled position uncertainty criteria.
 16. The method of claim 13, further comprising: transmitting the scaled position uncertainty criteria to the wireless terminal; receiving from the wireless terminal information comprising a reported position uncertainty parameter and a reported confidence parameter, the reported position uncertainty parameter being based on the scaled position uncertainty criteria and the reported confidence parameter being based on the confidence reporting characteristic of the wireless terminal; and re-scaling the reported position uncertainty parameter as a result of the confidence differential in a manner so that the position uncertainty criteria is satisfied, the reported position uncertainty parameter being based on the scaled position uncertainty criteria and the reported confidence parameter being based on the confidence reporting characteristic of the wireless terminal.
 17. The method of claim 16, re-scaling the reported position uncertainty parameter in accordance with the confidence differential.
 18. The method of claim 16, further comprising performing the scaling at a radio network controller (RNC) node.
 19. The method of claim 13, further comprising performing the scaling at an evolved Serving Mobile Location Center (eSMLC) node.
 20. The method of claim 13, further comprising the wireless terminal: performing the scaling; using the scaled position uncertainty criteria to determine a position parameter, position uncertainty parameter, and a confidence parameter; re-scaling the position uncertainty parameter to form a re-scaled uncertainty parameter that satisfies the position uncertainty criteria; and generating a position report comprising the position parameter, the re-scaled uncertainty parameter, and the confidence parameter.
 21. The method of claim 20, further comprising: in the position report expressing the position parameter in a polygon report format; and including in the polygon report format an information element comprising the reported confidence parameter.
 22. The method of claim 20, further comprising: in the position report expressing the position parameter in an ellipsoid point with uncertainty circle report format; and including in the ellipsoid point with uncertainty circle report format an information element comprising the reported confidence parameter.
 23. The method of claim 13, comprising using a computer-implemented scaler configured to scale the position uncertainty criteria to obtain the scaled position uncertainty criteria for use by the wireless terminal. 